The present invention is directed generally to solderless electrical connections and, more particularly, to a novel tool and method for terminating an insulated conductor into a portion of an electrical contact premounted in an electrical connector.
In recent years, increasing numbers of applications have developed in the communications, data processing and transportation industries requiring electrical connectors which provide reliable solderless interconnections with insulated electrical conductors. This demand has perhaps been greatest in the telecommunications industry where miniaturized, high contact density ribbon connectors are used extensively. Connectors of this general type are disclosed in U.S. Pat. Nos. 3,867,005; 3,902,154; and 3,926,498. Because of the great number of individual conductors terminated in these connectors and because of the close spacing between the individual contacts, reliable solder terminations are difficult to achieve, as well as time consuming and costly to maintain and service. For these reasons, insulation-piercing contacts have been developed for use in ribbon connectors and have met with wide acceptance when used to terminate insulated conductors having solid wire cores. Unfortunately, due to the demanding standards in the industry requiring almost negligible change in contact resistance, the insulation-piercing type ribbon connectors have proven unacceptable when used with stranded wire core conductors. Experience has shown that tensile forces applied to the conductors, as well as the cold flow of the insulation surrounding the core, causes the individual strands of the wire core to move and reposition within the insulation-piercing contacts, causing changes in contact resistance. Thus, solder termination ribbon connectors are still used widely with stranded core insulated conductors.
Accordingly, a need exists for a ribbon connector which provides a satisfactory solderless termination to stranded core insulated conductors, and preferably both stranded and solid core conductors can be used with the present invention. In addition, in order that the connector be commercially practicable, the termination can be performed with the electrical contact premounted within the connector.
One approach to solving these problems is shown in U.S. Pat. No. 4,159,156 which is assigned to the assignee of the present invention. In that patent, an electrical contact member having a terminal portion is premounted in an electrical connector. The terminal portion is formed by an outwardly open channel which has a pair of contact sidewalls and a pair of spaced conductor engaging elements in the form of opposed detents. The tool and method of that patent comprises shearing portions of the actual conductor engaging detent elements and bending the sheared portions onto the conductor.
Another termination tool and method is shown in pending U.S. application Ser. No. 042,465, filed May 25, 1979, which is a continuation of parent application Ser. No. 897,076, filed Apr. 17, 1978 and now abandoned and U.S. Pat. No. 4,264,118 which is a continuation of Ser. No. 897,076, both of which are assigned to the assignee of the present invention. In those pending applications, sidewall portions of the contact terminal portion, other than the conductor engaging detent elements (as in U.S. Pat. No. 4,159,156), are sheared and crimped onto the conductor which previously is inserted into the contact channel. However, in this application, a bifurcated termination tool head is employed to perform a two-step terminating operation whereby the conductor first is inserted into the contact and the sidewalls of the contact thereafter are crimped onto the conductor. The disclosure of these two pending applications is incorporated herein by reference for the general purpose of showing types of connector structures with which the present invention is applicable.